The team behind the All in One SEO Pack just released a new version of their popular WordPress plugin.

It is a security release patching two privilege escalation vulnerabilities we discovered earlier this week that may affect any web site running it.

The risks

If your site has subscribers, authors and non-admin users logging in to wp-admin, you are a risk. If you have open registration, you are at risk, so you have to update the plugin now.

While auditing their code, we found two security flaws that allows an attacker to conduct privilege escalation and cross site scripting (XSS) attacks.

In the first case, a logged-in user, without possessing any kind of administrative privileges (like an author of subscriber), could add or modify certain parameters used by the plugin. It includes the post’s SEO title, description and keyword meta tags. All of which could decrease one’s website’s Search Engine Results Page (SERP) ranking if used maliciously.

While it does not necessarily look that bad at first (yes, SERP rank loss is no good, but no one’s hurt at this point, right?), we also discovered this bug can be used with another vulnerability to execute malicious Javascript code on an administrator’s control panel. Now, this means that an attacker could potentially inject any javascript code and do things like changing the admin’s account password to leaving some backdoor in your website’s files in order to conduct even more “evil” activities later.

How to prevent this from happening

We’re not going to reinvent the wheel on this one: upgrade to the latest version available for this plugin.

Note: This plugin has not been installed by us on any of the Gecko Gully client sites (we prefer Yoast’s WordPress SEO because of it’s WooCommerce extension). However, it could have been installed since handover, or on other readers’ sites. Please update the plugin ASAP if you have it!